// sphere.h
//
// Copyright (C) 2003, 2004 Jason Bevins
//
// This library is free software; you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation; either version 2.1 of the License, or (at
// your option) any later version.
//
// This library is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
// License (License.md) for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with this library; if not, write to the Free Software Foundation,
// Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
// The developer's email is jlbezigvins@gmzigail.com (for great email, take
// off every 'zig'.)
//

#ifndef NOISE_MODEL_SPHERE_H
#define NOISE_MODEL_SPHERE_H

#include <assert.h>
#include "../module/modulebase.h"

namespace noise
{

  namespace model
  {

    /// @addtogroup libnoise
    /// @{

    /// @addtogroup models
    /// @{
    
    /// Model that defines the surface of a sphere.
    ///
    /// @image html modelsphere.png
    ///
    /// This model returns an output value from a Noise module given the
    /// coordinates of an input value located on the surface of a sphere.
    ///
    /// To generate an output value, pass the (latitude, longitude)
    /// coordinates of an input value to the GetValue() method.
    ///
    /// This model is useful for creating:
    /// - seamless textures that can be mapped onto a sphere
    /// - terrain height maps for entire planets
    ///
    /// This sphere has a radius of 1.0 unit and its center is located at
    /// the origin.
    class Sphere
    {

      public:

        /// Constructor.
        Sphere ();

        /// Constructor
        ///
        /// @param module The Noise module that is used to generate the output
        /// values.
        Sphere (const module::Module& module);

        /// Returns the Noise module that is used to generate the output
        /// values.
        ///
        /// @returns A reference to the Noise module.
        ///
        /// @pre A Noise module was passed to the SetModule() method.
        const module::Module& GetModule () const
        {
          assert (m_pModule != NULL);
          return *m_pModule;
        }

        /// Returns the output value from the Noise module given the
        /// (latitude, longitude) coordinates of the specified input value
        /// located on the surface of the sphere.
        ///
        /// @param lat The latitude of the input value, in degrees.
        /// @param lon The longitude of the input value, in degrees.
        ///
        /// @returns The output value from the Noise module.
        ///
        /// @pre A Noise module was passed to the SetModule() method.
        ///
        /// This output value is generated by the Noise module passed to the
        /// SetModule() method.
        ///
        /// Use a negative latitude if the input value is located on the
        /// southern hemisphere.
        ///
        /// Use a negative longitude if the input value is located on the
        /// western hemisphere.
        double GetValue (double lat, double lon) const;

        /// Sets the Noise module that is used to generate the output values.
        ///
        /// @param module The Noise module that is used to generate the output
        /// values.
        ///
        /// This Noise module must exist for the lifetime of this object,
        /// until you pass a new Noise module to this method.
        void SetModule (const module::Module& module)
        {
          m_pModule = &module;
        }

      private:

        /// A pointer to the Noise module used to generate the output values.
        const module::Module* m_pModule;

    };

    /// @}

    /// @}

  }

}

#endif
